<template>
  <div>
    <router-link
       tag="div"
       to="/"
       class="header-abs"
       v-show="showAbs">
      <div class="iconfont header-abs-back">&#xe675;</div>
    </router-link>
    <div
      class="header-fixed"
      v-show="!showAbs"
      :style="opacityStyle">
      <router-link to="/">
        <div class="iconfont header-fixed-icon">&#xe675;</div>
       </router-link>
        景点详情
    </div>

  </div>
</template>

<script>

  export default {
    name:'DetailHeader',
    data(){
      return{
        showAbs:true,
        opacityStyle:{
          opacity:0
        }
      }
    },
    methods:{
      handleScroll(){
        const top = document.documentElement.scrollTop
        if(top>60){
          let opacity = top / 140
          opacity = opacity > 1 ? 1 : opacity
          this.opacityStyle = { opacity }
          this.showAbs = false
        }else{
          this.showAbs = true
        }

      }
    },
    mounted() {
      window.addEventListener('scroll',this.handleScroll)
    },//页面展示时激活
    unmounted(){
       window.removeEventListener('scroll',this.handleScroll)
    }//页面被替换或隐藏时激活

  }
</script>

<style lang="stylus" scoped>
  @import '~styles/varibles.styl'
  .header-abs
    position :absolute
    left :.2rem
    top:.2rem
    width :.8rem
    height :.8rem
    text-align :center
    line-height :.8rem
    border-radius :.4rem
    background :rgba(0,0,0,.8)
    .header-abs-back
      color :#fff
      font-size :.4rem
  .header-fixed
    z-index :2
    position :fixed
    top :0
    left :0
    right :0
    height :$headerHeight
    line-height :$headerHeight
    text-align :center
    background :$bgColor
    font-size :.32rem
    color: #fff
    .header-fixed-icon
     position :absolute
     top :0
     left :0
     width :.64rem
     text-align :center
     font-size .4rem
     color:#fff
</style>
